So here's a list of the things I am looking to do in the future. It's not really in any order except the first. Let me know if you have any ideas for development!
Have the forum indexed and the mod added to the Downloads section for better visibility.
Get more people to play the current version of the mod so any lingering issues may be addressed.
Overhaul the entire enemy AI section so that I can do some more interesting things with enemies.
Take a look at enemy stats once again to try and create varied combat situations.
Potentially change the glove/ring equipment slot to an accessory slot more similar to the one found in FFV. This would open up the possibility for some status/elemental immunities earlier in the game.
Replace Rydia and Kain's secondary commands with something a bit more useful.
Add some lore-friendly super-bosses to the game.
Squash bugs.

We are pleased to announce that NG+ is now hosting @praetarius5018 's latest mod, Final Fantasy V: Void Divergence! Void Divergence brings many exciting features to Final Fantasy V such as all-new ATB mechanics, including !Brave and !Def abilities which drastically alter strategy in combat. @praetarius5018 also provides us with a major rebalance, an overhaul of abilities and enemies, the addition of a New Game Plus mode, and much more!
You can find more information on the mod and download it here! http://ngplus.net/index.php?/files/file/50-final-fantasy-v-void-divergence/
Check out Void Divergence's subforum here! http://ngplus.net/index.php?/forums/forum/34-final-fantasy-v-void-divergence/

Glad to hear you maybe, possibly enjoyed it?
The mod you're thinking of is Unprecedented Crisis. I toyed around with trying to get party swaps late-game, but the technical limitations are too vast.
I've thought about adding more content into the mod, but at this point I've been pretty busy and it wouldn't be more than some superbosses or other minor content. I did tool around with the idea of a sequel using FFVI as the base game, but I just don't have the time to learn another editor and the quirks for another game.
Also, seeing as you're the first person to comment in quite some time, I don't feel terribly motivated since my project is probably the least popular on the site.

Game is about the same length as the original, maybe slightly shorter if you're familiar with the mechanics.
I would imagine the running option of the mod would work, but I'm not too sure about the other stuff. I didn't do too much to the battle engine, so I'm skeptical to say yes or no. All I'll say is if you try it and weird stuff starts happening that it probably doesn't work.

I was thinking something super bite-sized, like a single level/stage for a platformer, dungeon for an RPG, and even include things like UI changes for games, music tracks, or artwork for those more artistically inclined.

You're pretty much at the endgame, yes. The Hummingways give you hints to other sidequests in the game. There's a pseudo-hidden thing you have to do to complete the rest of the sidequests; you've already done half of it. I can fill you in if you get stumped.
As for Titan, there's only one cave nearby Toroia...

Your Cecil may have been wearing the FireWard shield, which makes him weak to Ice (this status flip-flop is hard-coded to the game). Ice and water share elements in FFIV, so that could explain that.
Thanks for pointing out the typo. I feel like I did a pretty good job with the text and dialogue in the game, but every now and then someone points out a dumb mistake I made. I did a lot of work on this game in the wee hours of the morning, so the corrections are very much appreciated.
Red Worms use both Drain and Vampire. Drain is a spell (noted by the icon next to it when cast), but Vampire is not. Silence will prevent Drain, but you cannot silence enemy skills like Vampire.
The Baron gauntlet used to be brutal until I was convinced to tone it back some during beta.
You can always put Rosa, Rydia, and Edge in the back row with the rest of the party in the front. Edge is pretty strong as it is, and it doesn't affect his damage too terribly. He also has ranged weapon options as well as Throw and Ninja ignoring row.
The inventory management in FF games before V was really bad. I think IV was the first to introduce buying of multiples, so it was a bit clunky (just like the whole shop interface). It's also the reason I made access to the Fat Chocobo free. It can be a bit bothersome to have to lug your stuff around to the Fat Chocobo every now and then, but it's worth it over the hassle of playing inventory Jenga constantly.
FFIV is one of the shorter FF games, but you still have a bit to go as well as quite a few optional sidequests. Very happy to hear that you're thoroughly enjoying it!

Welcome to NG+!
You can actually buy items in different quantities at shops by hovering over the 10, then pressing up, down, or the X button. This will change the quantity by +1, -1, or +10 respectively.
1. This was a limitation of the original game. For some reason, the float status doesn't carry over between floors. Not sure how to make it slightly more permanent.
3. Yes, if the animation plays that means the spell worked. Slow works on pretty much everything and stacks up to three times. Poison is the only other negative status that will work on bosses, and that's due to a bug that was also present in vanilla.

I went with DrkWv instead of Dark to describe it a bit better. Five character limits really suck.
The beginner equipment for most characters is just to give you an idea of what they can use. Stats are also only able to be increased by +3/5/10/15 or negatives of those (which only one item has).
Edge is pretty decent at clearing flan encounters early-on, but you'll likely need to use MP restoring items. With regards to Edge's power, yes, he is very strong offensively. He is also the most defensively weak (though back row makes him a bit less squishy). It's difficult to buff other characters without making the game feel too easy or nerfing Edge and making him feel useless.
I tried to have Cecil's gear stick to his character when he becomes a Paladin, but it lead to issues such at the game ignoring his Paladin starting equipment among other things.
I mean, the Excalibur is a giant hunk of metal, so...
The Adamant Armor is obtained the usual way. I upped the drop rate on the tail, but left the encounter rare. I'm not too concerned with the readme being slightly misleading for that one piece of gear.
Thanks for playing! Hope you enjoyed it.

Version 1.07d has been released! This version addresses more minor bugs with item indeces and adds a new curative item. Please check the Readme for installation instructions.
Download the mod here!
Saves from versions prior to 1.07 WILL NOT be compatible with 1.07d. Please start a new game before beginning on this patch version.
Changes for 1.07d are in the Spoiler tags below.

Glad you found your way back to the Underworld. Always feels rewarding when you're able to figure things out on your own.
The note about King Eblan not being present was because his character index is shared with the King of Baron's. If I enabled one I would have to enable the other, so I just had to "conveniently" write him out.